You can try to negotiate the balance of the term byt technically you are responsible for the enitire period whether you decide to return it early or not.
The pratical solution is to get the pay-off value, then advertise the car for that amount
If you find a willing buyer, bring him to the finance company, have him pay the entire balance, and then when you get the receipt, give hima copy together with the deed of sale
Even if it is a straight lease, you can get the pay-off value.
Never never agree to an assignment/continue payment or assume mortgage/assume lease etc. Because you are never legally released from the principal obligation
There are no legal safeguards
Payoff is the only solution, the only solution